With rapid development of communications technologies, coexistence and development of various types of wireless network cells become a development trend in future communications networks; therefore, a cell in multi-point convergence is gradually introduced to a wireless network. In a network in multi-point convergence, a coverage area of the network is formed by cells of different sizes and types, and the cells include a macro cell, a small cell, and the like. A coverage area of a macro cell includes coverage areas of multiple small cells, where the small cells are generally discretely set in the macro cell. Most macro cells use a low frequency band carrier, which features a continuous coverage area, so that seamless coverage is implemented among the macro cells. However, low frequency resources are scarcer. With popularization of terminals such as smartphones, users impose a higher requirement for a wireless transmission rate. To meet the users' requirement, a high frequency band carrier with abundant resources needs to be gradually used to provide a service. Because a high frequency band carrier features a small coverage area, a base station that uses a high frequency band carrier to implement small coverage is generally referred to as a small eNodeB (SeNB, Small eNB), and sometimes the small eNodeB is also referred to as a secondary eNodeB, that is, a secondary eNB, which may also be abbreviated to SeNB. A coverage area of the small eNodeB is generally referred to as a small cell. Although a coverage area of a high frequency band carrier is smaller, resources are relatively abundant.
In traditional 2G and 3G networks, a carrier at a lower frequency band is generally used. For example, a macro cell is used to provide a service for a user. When network load of the macro cell is heavier, a terminal may be handed over to a corresponding small cell to offload network services, so as to increase a network capacity. Currently, to increase a transmission rate of a wireless network and improve user experience, network enhancement in a small cell has become a research topic. A main idea of small cell enhancement is that user equipment (UE, User Equipment) may obtain more available wireless resources by simultaneously aggregating carriers from a macro cell and a small cell, thereby increasing a data transmission rate. Currently, a possible orientation is that a macro eNodeB (MeNB, macro eNB) is used as a main control station responsible for mobility management of user equipment, data packet offloading, and the like. In a case in which a macro eNodeB is used as a main control station, the macro eNodeB is sometimes also referred to as a master eNodeB, that is, a Master eNB, which may also be abbreviated to MeNB. When user equipment simultaneously works in a macro eNodeB and a small eNodeB, because distances from the two base stations to the user equipment are different, when the user equipment performs uplink data transmission, different uplink timing advances (TA, timing advance) are generally required to send uplink data. Generally, all cells in the macro eNodeB may be grouped into a cell group, and when the user equipment performs uplink data transmission in the cell group, a same TA value is used. Therefore, the group of cells that use the same TA sometimes is also referred to as a TA group (TAG Timing advance Group). Likewise, a cell controlled by a small eNodeB may also be used as a TA group, and when user equipment performs uplink data transmission in cells in different TA groups, TA values corresponding to these TA groups are used for transmission. Correspondingly, when a macro eNodeB or a small eNodeB configures one or more cells in a TA group for user equipment for data transmission, these cells are generally referred to as secondary cells (Secondary Cell, SCell).
When user equipment simultaneously works in two base stations, that is, a macro eNodeB and a small eNodeB, if the macro eNodeB and the small eNodeB each independently configure one or more secondary cells for the user equipment, a secondary cell index (SCell index) of a secondary cell configured by the macro eNodeB may be the same as a secondary cell index of a secondary cell controlled by the small eNodeB. In this case, if the user equipment receives an operation related to the secondary cell, a misoperation may occur because of a conflict between the secondary cell indexes of the two base stations. For example, when a command for activating a secondary cell of the macro eNodeB is received, a secondary cell of the small eNodeB may be incorrectly activated; or when a timing adjustment command for a TAG of a secondary cell of the macro eNodeB is received, timing of a TAG of a secondary cell of the small eNodeB may be incorrectly adjusted. In a case in which timing adjustment is incorrectly performed, the UE uses incorrect uplink timing to perform transmission. Consequently, not only a signal of the UE itself cannot be correctly received by a base station, but also severe interference may be brought to uplink transmission of another UE. Currently, one solution is: When an operation such as activating a secondary cell is being performed, an identifier of a station to which the secondary cell belongs is clearly indicated in a related message, so as to help user equipment to clearly determine whether each of two secondary cells with a same secondary cell index belongs to a macro eNodeB or a small eNodeB. However, this causes that a related message or related signaling needs to carry a device identifier of a base station each time, leading to heavier load of the message.